Device for compression across fractures

ABSTRACT

A bone fixation device includes a first element extending from a first head to a first shaft along a first longitudinal axis and having a first channel extending therethrough. The first head rests against a portion of bone adjacent to a first hole through which the first shaft is inserted. A second element includes a second shaft extending along a second longitudinal axis to a second head and having a second channel extending therethrough, the second head resting against a portion of bone adjacent to a second hole through which the second shaft is inserted. The second channel is dimensioned to receive the first shaft therein. A tensioning element is insertable through the first and second channels so that tension applied at a second end thereof imparts a compressive force to the a bone into which the first and second elements are inserted.

PRIORITY CLAIM

The present application is a Continuation Application of U.S. patentapplication Ser. No. 13/693,603 filed on Dec. 4, 2012, now U.S. Pat. No.9,011,501, which claims the priority to U.S. Provisional PatentApplication Ser. No. 61/570,527 filed on Dec. 14, 2011. The entiredisclosure of these patents/applications are expressly incorporatedherein by reference.

BACKGROUND INFORMATION

Fractures of the pelvis and, more specifically, of the sacroiliac jointare often treated by inserting a fixation device across the fracturesite. Present fixation systems and methods are generally directed to theinsertion of one or more sacral bars or cancellous screws across thefracture site. The sacral bars are formed as elongated planar rodspassed through the pelvis posterior to the sacrum until a free, end ofthe rod extends out of an opposing wall of the pelvis. Threaded nuts arethen screwed onto the ends of the sacral bar to create and maintaincompression of the pelvis. Cancellous screws can be inserted to spanacross the pelvis or can be inserted from either side of the pelvis tomaintain the stability of the sacroiliac joint. However, these screwsrely heavily on an overall strength of the bone and thread purchase tomaintain the compression of the pelvis. These devices are thereforesusceptible to failure due to loss of bone strength (e.g., due toosteoporosis, etc.), loosening of the threaded bolts and/or a loss ofbony purchase (e.g., through rotational and/or longitudinal movement ofthe sacral bars within the bone).

SUMMARY OF THE INVENTION

The present invention is directed to a bone fixation device comprising afirst element extending from a first head at a first end to a firstshaft at a second end along a first central longitudinal axis and havinga first channel extending therethrough, the first head extendingtransverse to the first shaft providing a first shoulder which, in anoperative configuration, rests against a portion of bone adjacent to afirst hole through which the first shaft is inserted to define a maximumextent to which the first element may be inserted into the hole. Thebone fixation device also comprises a second element including a secondshaft extending along a second central longitudinal axis from a thirdend to a head at a fourth end thereof and having a second channelextending therethrough, the second head extending transverse to thesecond shaft providing a second shoulder which, in an operativeconfiguration, rests against a portion of bone adjacent to a second holethrough which the second shaft is inserted to define a maximum extent towhich the second element may be inserted into the second hole, thesecond channel being dimensioned to slidably receive the first shafttherein. The bone fixation device also comprises a tensioning elementinsertable through the first and second channels, the tensioning elementincluding a first end sized to prevent the first end from entering oneof the first and second channels so that, tension applied at a secondend of the tensioning element imparts a compressive force to the firstand second elements and, consequently to a bone into which the first andsecond elements are inserted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first perspective view of a exemplary bone fixationelement according to the present invention in a first configuration;

FIG. 2 shows a perspective view of the bone fixation element of FIG. 1in a second configuration;

FIG. 3 shows a second perspective view of the bone fixation element ofFIG. 1;

FIG. 4 shows a perspective view of the bone fixation element of FIG. 1in an implanted configuration; and

FIG. 5 shows a side view of the bone fixation element of FIG. 1 in animplanted configuration.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. The present inventionrelates generally to devices and methods for the fixation of a fracturedor otherwise damaged pelvic bone. Specifically, the present inventionrelates to methods and devices for inserting a bone fixation elementinto the bone. The exemplary bone fixation element according to theinvention comprises a first elongated element and a second elongatedelement, each extending along a longitudinal axis. In an operativeconfiguration, the first and second elements are inserted through firstand second lateral openings provided on opposing sides of a pelvic bone.In one embodiment, the first and second lateral openings can be two endsof a single hole formed by drilling completely across the pelvis. Inanother embodiment, two openings may be drilled on opposing walls of thepelvis. A free end of the first element is then inserted into a channelextending through the second element until the first and second elementsare securely seated against the pelvic bone. A cable is then insertedthrough the first and second elements. A first end of the cablecomprises a cable stop configured to lockingly engage an opening on alateral head of the first element. The cable is then locked in positionat a lateral end of the second element using a crimp to secure the firstand second elements in a desired position relative to one another andcompress the fractured bone, as will be described in greater detaillater on. It is noted that although the exemplary system and method arediscussed with respect to a sacroiliac fixation system and method, theinvention may be used in any other bone fixation procedure in any otherbone of the body by modifying the dimensions and shape of the apparatusto suit the particular anatomy. The term “medial” as used herein refersto a direction approaching a medial plane of a body in an operativeconfiguration while the term “lateral” refers to a direction extendingaway from the medial plane in a right and left direction.

As shown in FIGS. 1-5, a bone fixation device 100 according to anexemplary embodiment of the invention comprises a first element 102 anda second element 104. The first element 102 extends from a lateral end106 to a medial end 108 along a central longitudinal axis 110. The firstelement 102 according to this embodiment is substantially cylindricaland comprises a lateral body portion 112 having a first outer diameterand a medial body portion 114 having a second outer diameter, the secondouter diameter being smaller than the first outer diameter. An elongatedfirst channel 116 extends through the first element 102 from the lateralend 106 to the medial end 108. The first channel 116 is in longitudinalalignment with the longitudinal axis 110 and is configured anddimensioned to receive a cable 200 therethrough, as will be described ingreater detail later on. The lateral end 106 comprises an increaseddiameter head 118 having an oblong cross-sectional shape. It is noted,however, that any other cross-sectional shape (e.g., oval, circular,rectangular, etc.) may be used without deviating from the scope of theinvention. The head 118 also comprises an opening 120 extendingtherethrough, a hole axis of the opening 120 extending substantiallyparallel to the longitudinal axis 110. In another exemplary embodiment,the hole axis of the opening 120 may extend at any other angle relativeto the axis 110. The opening 120 is positioned adjacent to the channel116. As shown in FIGS. 4-5, the head 118 may also comprise a countersunkportion 121 configured to aid in manipulation of the cable 200, as willalso be described in greater detail below.

The second element 104 extends from a lateral end 122 to a medial end124 along the central longitudinal axis 110. The second element 104according to this embodiment is substantially cylindrical in shape andcomprises a substantially uniform outer diameter which is substantiallyequivalent to the first outer diameter of the lateral body portion 112.However, those skilled in the art will understand that the first andsecond elements 102, 104, respectively, may take any desired shape solong as the medial body portion 114 is slidably receivable within anelongated second channel 126 extending through the second element 104.The second channel 126 extends from the lateral end 122 to the medialend 124 in longitudinal alignment with the longitudinal axis 110 and isconfigured and dimensioned to permit insertion of the medial bodyportion 114 thereinto. In one exemplary embodiment, the channel 126 hasa substantially uniform diameter substantially equivalent to the outerdiameter of the medial body portion 114 with a slight clearance topermit the medial body portion 114 to slide therein. In anotherexemplary embodiment, as shown in FIG. 3, the channel 126 comprises amedial channel portion 128 and a lateral channel portion 130. The medialchannel portion 128 has a diameter substantially equivalent to orgreater than second outer diameter of the medial body portion 114 andsmaller than the first outer diameter of the lateral body portion 112.This configuration permits the insertion of the medial body portion 114into the channel 126 while preventing the lateral body portion 112 frombeing inserted therein. In an exemplary embodiment, the first and secondportions 102, 104 are dimensioned so that, when inserted to an operativeconfiguration, the medial body portion 114 is seated within the medialchannel portion 128 with enough overlap to maintain stability. Varying alength of the overlap allows adjustment of the length of the device 100to account for variations in anatomy in different patients. In anotherembodiment, the device 100 may be provided in a variety of lengths sothat a physician may select a device having a length range conforming tothe requirements of a particular procedure. In a preferred embodiment,the device 100 may be configured to prevent the medial body portion 114from being fully seated in the medial channel portion 128. That is, byhaving the medial body portion 114 only partially seated in the medialchannel portion 128, a greater amount of compression may be applied viathe cable 200, as will be described in greater detail later on. Thelateral channel portion 130 has substantially the same diameter as thefirst channel 116 so that the cable 200 inserted through the device 100follows a smooth, substantially unobstructed path. The lateral end 122comprises an increased diameter head 132 having an oblongcross-sectional shape similar to the shape of the head 118. It is noted,however, that the head 132 may comprise any other shape withoutdeviating from the scope of the invention. The head 132 comprises anopening 134 extending therethrough, a hole axis of the opening 134extending substantially parallel to the longitudinal axis 110. As withthe opening 120, the hole axis of the opening 134 may also extend at anyangle relative to the axis 110.

In accordance with an exemplary method according to the invention, aphysician or other user makes incisions open to the right and leftlateral walls of a pelvis. The fracture is then reduced andprovisionally stabilized using, for example, Kirschner wires, as thoseskilled in the art will understand. A drill may then be used to form atleast one longitudinal hole through the pelvis. A guide wire may firstbe inserted in the desired portion of the bone in a target insertionorientation. A cannulated drill may then be guided over the guide wireto open the bone to a desired diameter selected to accommodate thedevice 100, as those skilled in the art will understand. In an exemplaryembodiment, two holes may be drilled through the pelvis across thefracture to receive two devices 100, although any number of holes may bedrilled to conform to the requirements of the particular procedure, asthose skilled in the art will understand. The cable 200 having the cablestop 202 on a first end thereof is then inserted into the opening 120 ofthe first element 102. The cable stop 202 may be an enlarged end portionof the cable 200 having a diameter greater than a diameter of theopening 120. In an exemplary embodiment, the cable stop 202 is insertedinto the opening 120 from a medial direction so that when the firstelement 102 is positioned in the bone, the cable stop 202 is positionedtoward the bone. As those skilled in the art will understand, thisconfiguration minimizes stresses applied to the cable stop 202 in anoperative configuration and helps to prevent loosening of the cable 200relative to the bone. The first and second elements 102, 104 may then beinserted into the drilled hole from the left and right walls of thepelvis, respectively, until the medial body portion 114 is seated withinthe medial channel portion 128, as described in greater detail earlier.In this configuration, the heads 118, 132 are in contact with the pelvisand the cable stop 202 is positioned adjacent the bone, as shown in FIG.3. The cable stop 202 is seated within the concave portion of the head118 so the head 118 is in direct contact with the bone withoutinterference from the cable stop 202. The free end of the cable 200 (notshown) is then inserted into the channel 116 from the lateral end 106,forming a loop 204 adjacent the head 118. As those skilled in the artwill understand, the cable 200 may be configured and dimensioned tominimize a protrusion of the loop 204 out of the head 118 thereforeminimizing a profile of the implanted device 100. The loop 204 aids inremoval of the device 100 from the body, as will be described in greaterdetail later on. The cable 200 is guided through the channel 116 andchannel 126 until the free end exits the lateral end 122. The free endof the cable 200 is then inserted into the opening 134 from the lateralend. A crimp is then advanced over the free end of the cable 200 andadvanced until it contacts the head 132 of the second element 104. Thecrimp may be any crimp known in the art. A tensioning mechanism threadedover the free end of the cable 200 is then operated as would beunderstood by those skilled in the art to apply a desired tension to thecable consequently applying a desired compressive force to the bone. Thecrimp is then crushed in a known manner to maintain the desired tensionon the cable and the free portion of the cable 200 extending away fromthe crimp is trimmed. As would be understood by those skilled in theart, the countersunk portion 121 provides a space for into which thecable cutter may be advanced to allow a cable cutting device to snip thecable close in minimizing the protrusion of the free end of the cable200.

A physician may decide to remove the device 100 from the body after apredetermined amount of time has elapsed (e.g., once the bone hashealed, etc.). To remove the device, a cable cutting mechanism may beused to cut the loop 204, thereby removing the compressive force appliedon the bone by the device 100. The device 100 and cable 200 may then beremoved from the body.

It will be apparent to those skilled in the art that various othermodifications and variations may be made in the structure and themethodology of the present invention, without departing from the spiritor scope of the invention. For example, the exemplary system and methoddisclosed herein may be used for the treatment of any bone fracturewherein compression is required and opposing ends of the fractured boneare accessible to the physician. For example, the exemplary system andmethod may be used for the fixation of fractures of a patella, condyle,etc., wherein the compression may be aided by any number of additionalbone fixation devices (e.g., intramedullary nail) without deviating fromthe scope of the invention. Thus, it is intended that the presentinvention cover modifications and variations of the invention providedthat they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A bone fixation device, comprising: a firstelement including a first head and a first shaft extending along a firstcentral axis from a first end connected to the first head to a secondend, the first element including a first channel extending therethrough,the first head extending transverse to the first shaft to provide afirst shoulder which, in an operative configuration, rests against aportion of bone adjacent to a first hole through which the first shaftis inserted to define a maximum extent to which the first element may beinserted into the first hole, the first head including a first openingextending therethrough adjacent to the first channel; a second elementincluding a second head and a second shaft extending along a secondcentral axis from a first end connected to the second head to a secondend, the second element including a second channel extendingtherethrough, the second head extending transverse to the second shaftto provide a second shoulder which, in an operative configuration, restsagainst a portion of bone adjacent to a second hole through which thesecond shaft is inserted to define a maximum extend to which the secondelement may be inserted into the second hole, the second channel sizedand shaped to receive the first shaft therein; and a tensioning elementinsertable through the first opening and through the first and secondchannels, the tensioning element including a first end sized to preventthe first end from passing through the first opening so that, tensionapplied at a second end of the tensioning element applies a compressiveforce to a bone through which the first and second elements areinserted.
 2. The device of claim 1, wherein the first opening extendsthrough the first head along an axis substantially parallel to the firstcentral longitudinal axis.
 3. The device of claim 1, wherein the firstopening extends through the first head at an angle smaller than 90degrees relative to the first central longitudinal axis.
 4. The deviceof claim 1, wherein the second head includes a second opening extendingtherethrough adjacent to the second channel, the second opening sizedand shaped to permit the second end of the tensioning element to bepassed therethrough.
 5. The device of claim 4, wherein the secondopening extends through the second head along an axis substantiallyparallel to the second central longitudinal axis.
 6. The device of claim4, wherein the second opening extends through the second head at anangle smaller than 90 degrees relative to the second centrallongitudinal axis.
 7. The device of claim 1, wherein the first headincludes a first countersunk portion.
 8. The device of claim 1, whereinthe second head includes a second countersunk portion.
 9. A method forbone fixation, comprising: inserting a tensioning element through afirst opening extending through a first head of a first element so thatan enlarged first end of the tensioning element, which is larger thanthe first opening, abuts a surface of the first head; inserting a firstshaft of the first element into a first hole in a bone until the firsthead rests against a portion of bone adjacent to the first hole, thefirst shaft extending along a first central axis from a first endconnected to the first head to a second end, the first element includinga first channel extending therethrough, the first opening extendingadjacent to the first channel; inserting a second shaft of a secondelement into a second hole in the bone until a portion of the firstshaft is received within a second channel extending through the secondelement and a second head of the second element rests against a portionof bone adjacent to the second hole, the second shaft extending along asecond central axis from a first end connected to the second head to asecond head; inserting a second end of the tensioning elements throughthe first and second channels so that the tensioning element forms afirst loop adjacent the first head and the second end of the tensioningextends past the second head; and applying tension to the tensioningelement to provide a compressive force to the bone in which the firstand second elements are inserted.
 10. The method of claim 9, furthercomprising inserting the second end of the tensioning element through asecond opening extending through the second head adjacent to the secondchannel so that the tensioning element forms a second loop adjacent thesecond head.
 11. The method of claim 10, further comprising securing thetensioning element to the first and second elements to maintain thecompressive force applies to the bone.
 12. The method of claim 11,wherein securing the tensioning element includes advancing a crimp overthe second end of the tensioning member and crushing the crimp adjacentthe second head.
 13. The method of claim 9, wherein the enlarged firstend of the tensioning element is seated within a concave portion of thefirst head.
 14. The method of claim 9, further comprising cutting a freeportion of the tensioning element.
 15. The method of claim 11, furthercomprising removing the compressive force to the bone by cutting one ofthe first and second loops of the tensioning element.